Category Archives: Earth

This image from the Solar Dynamics Observatory shows the X6.9 solar flare of Aug. 9, 2011 near the western limb (right edge) of the sun. CREDIT: NASA/SDO/Weather.com

Solar flares like the huge one that erupted on the sun early today (Aug. 9) will only become more common as our sun nears its maximum level of activity in 2013, scientists say.

Tuesday’s flare was the most powerful sun storm since 2006, and was rated an X6.9 on the three-class scale for solar storms (X-Class is strongest, with M-Class in the middle and C-Class being the weakest).

Flares such as this one could become the norm soon, though, as our sun’s 11-year cycle of magnetic activity ramps up, scientists explained. The sun is just coming out of a lull, and scientists expect the next peak of activity in 2013. The current cycle, called Solar Cycle 24, began in 2008.

“We still are on the upswing with this recent burst of activity,” said Phil Chamberlin, a solar scientist at NASA’s Goddard Space Flight Center in Greenbelt, Md., who is a deputy project scientist for the agency’s Solar Dynamics Observatory, a sun-studying satellite that launched in February 2010. “We could definitely in the next year or two see more events like this; there’s a potential to see larger events as well.”

A more active sun

Earth got lucky with the most recent flare, which wasn’t pointed directly at Earth; therefore, it didn’t send the brunt of its charged particles toward us, but out into space. However, we may not be so fortunate in the future, experts warned.

“We’re in the new cycle, it is building and we’ll see events like this one,” said Joe Kunches, a space scientist with the National Oceanic and Atmospheric Administration (NOAA)’s Space Weather Prediction Center. “They’ll be much more commonplace and we’ll get more used to them.”

Spacecraft such as the Solar Dynamics Observatory (SDO), which recorded amazing videos of the Aug. 9 solar flare, and other observatories will be vital in monitoring the sun during its active phase, researchers said.

How sun storms form

Storms brew on the sun when pent-up energy from tangled magnetic field lines is released in the form of light, heat and charged particles. This can create a brightening on the sun called a flare, and is also often accompanied by the release of a cloud of plasma called a coronal mass ejection (CME).

These ejections are the part we Earthlings have to worry about.

As the CME careens through space, it can send a horde of charged particles toward our planet that can damage satellites, endanger astronauts in orbit, and interfere with power systems, communications and other infrastructure on the ground.

“We’re well aware of the difficulties and challenges,” Kunches told SPACE.com. “We know more about the sun than we ever have.”

Can we predict solar storms?

When a big storm occurs, the Space Weather Prediction Center releases a warning to the U.S. Department of Homeland Security, emergency managers and agencies responsible for protecting power grids. Then power grids can distribute power and reduce their loads to protect themselves.

Satellite and power companies are also trying to design technology that can better withstand the higher radiation loads unleashed by solar storms.

Still, scientists would like to offer more advanced warnings when big storms are headed our way.

“We’re being reactive, we’re not being proactive,” Chamberlin said. “We don’t know how to predict these things, which would be nice.”

Chamberlin said solar science has come a long way in recent years, though, and the goal of SDO and other NASA projects is to improve our understanding of the sun and our ability to forecast space weather.

You can follow SPACE.com senior writer Clara Moskowitz on Twitter @ClaraMoskowitz. Follow SPACE.com for the latest in space science and exploration news on Twitter @Spacedotcom and on Facebook.

Ever since the Voyager 2 data confirmed the nonsymmetrical shape of the solar system scientists have pondered its cause (i). In summary, the edge of the heliosphere (the place where the solar wind slows to sub sonic speeds) appears to be 1.2 billion kilometers shorter on the south side of the solar system (and in the general direction of the winter solstice, the direction of Voyager 2), than it is on the edge of the planetary plane (where Voyager 1 exited approximately a year earlier). This indicates the heliosphere is not a sphere at all but a bullet shape. More data is required to determine the exact shape in all directions.

The initial explanation was there must be some sort of gas cloud pressing against one side of our solar system. While this hypothesis is plausible there is another possibility that deserves consideration; stellar wind.

The sun’s solar winds are primarily driven by its magnetic field. When magnetic storms arise on the sun it produces coronal mass ejections (CME’s), which are like waves or ripples on the solar wind. The solar wind is constantly pushing on the daylight side of the earth’s magnetosphere squashing it in a pattern similar to the way the sun’s magnetic field seems to be squashed where Voyager 2 exited the solar system. Thus it is possible that the dented solar system might be due to the same type of cause; stellar winds from a not too distant star.

Some indication of this might reside in the data recently received by NASA’s sun-focused STEREO spacecraft. The twin STEREO spacecraft were launched in 2006 into earth’s orbit about the sun to obtain stereo pictures of the sun’s surface and to measure magnetic fields and ion fluxes associated with solar explosions. Between June and October 2007, the STEREO spacecraft detected atoms “originating from the same spot in the sky: the shock front and the heliosheath beyond, where the sun plunges through the interstellar medium”, and found “energetic neutral particles from beyond the heliosphere” that are moving toward the sun (ii). While this might be due to other causes such as “charge exchange between hot ions and neutral atoms” as hypothesized by scientists at UC Berkeley, it may also indicate the source of the asymmetrical solar system is due to the stellar wind from another star rather than an interstellar gas cloud. More data is needed and should be forthcoming with the pending launch of the Interstellar Boundary Explorer (IBEX), due to begin receiving data some time in the next year.

A team of Italian scientists has announced seismic evidence of what could be meteor fragments beneath Lake Cheko in Siberia–the first “solid evidence” of a Tunguska asteroid.

Lake Cheko in the Siberian region of Tunguska has recently emerged as a candidate for an “impact site” linked to the famous Tunguska explosion of 1908. Credit: www-th.bo.infn.it/tunguska / University of Bologna

On June 30, 1908, a massive explosion detonated in the skies over Tunguska in northern Siberia. The resulting shock wave flattened some 60 million trees across 2000 square kilometers. The blast was heard hundreds of miles away and the cloud of dust colored the skies of the Northern Hemisphere for months afterwards.

The first expedition to investigate the region could not locate any sign of an impact event, nor did it recover any meteoric fragments. A later expedition, however, did uncover magnetite globules and various forms of silicate globules embedded in the earth and in the trees.

Most scientists eventually settled on either an icy comet explosively vaporized before reaching the surface, or a small rocky asteroid exploding in the atmosphere and leaving no appreciable fragments. But the absence of definitive evidence for an impact invited many exotic theories–ranging from “mirror-matter” or a tiny “quantum black hole,” to an exploding alien craft or a Nikola Tesla experiment gone awry.

In past discussions of the Tunguska event, our Picture of the Day editors have suggested electric discharge between a small comet or asteroid and the Earth. That suggestion was based on a wide variety of recorded physical effects and the testimony of human witnesses.

More recently, however, a team of Italian researchers has suggested that the 164-foot deep Lake Cheko, five miles northwest of the epicenter of the blast, could be the site of an impact by a meteor or a fragment of the body responsible for the devastating Tunguska event.

The team reported that 3D sonar images of the lake’s bottom indicate that it is funnel-shaped, something that might be expected of both an impactor and an electric discharge. Using seismic detectors, the University of Bologna scientists discovered an area of greater density beneath the lake, noting that this could indicate the remains of a meteor. “When we looked at the bottom of the lake, we measured seismic waves reflecting off of something,” said Giuseppe Longo, a physicist at the University of Bologna in Italy and co-author of the study. “Nobody has found this before. We can only explain that and the shape of the lake as a low-velocity impact crater.”

According to a report on the Space.com web site, however, some physicists are skeptical about the small size of the Lake Cheko crater. “We know from the entry physics that the largest and most energetic objects penetrate deepest,” said David Morrison, an astronomer with NASA’s Ames Research Center. Morrison wondered aloud why only a fragment of the main explosion would reach the ground to make a relatively small crater, while the greater portion would not create a larger main crater.

But Alan Harris, a planetary scientist at the Space Science Institute, points out that, in 1947, the Russian Sikhote-Alin meteorite created 100 small craters. Some were 20 meters (66 feet) across. A site in Poland also exists, he explained, where a large meteor exploded and created a series of small lakes. “If the fragment was traveling slowly enough, there’s actually a good chance [the Italian team) will unearth some meteorite material,” Harris said.

The researchers will return to Tunguska this summer with plans to drill beneath the bottom of Lake Cheko, hoping to find a meteorite. From an Electric Universe perspective, if the Tunguska explosion was the result of an electric discharge, a meteor fragment may indeed be found, pointing to the source of the discharge. But more likely, the increased density beneath the lake could be the signature of the electric arc that excavated the depression, producing the fused sands and soils of a fulgurite.